Dhcp Address Pool - H3C S5600 Series Operation Manual

Operation Manual – DHCP
H3C S5600 Series Ethernet Switches

2.1.2 DHCP Address Pool

A DHCP address pool holds the IP addresses to be assigned to DHCP clients. When a
DHCP server receives a DHCP request from a DHCP client, it selects an address pool
depending on the configuration, picks an IP address from the pool and sends the IP
address and other related parameters (such as the IP address of the DNS server, and
the lease time of the IP address) to the DHCP client.
I. Types of address pool
The address pools of a DHCP server fall into two types: global address pool and
interface address pool.
A global address pool is created by executing the dhcp server ip-pool command
in system view. It is valid on the current device.
If an interface is configured with a valid unicast IP address, you can create an
interface-based address pool for the interface by executing the dhcp select
interface command in interface view. The IP addresses an interface address pool
holds belong to the network segment the interface resides in and are available to
the interface only.
II. Structure of an address pool
The address pools of a DHCP server are hierarchically organized in a tree-like structure.
The root holds the IP address of the natural network segment, the branches hold the
subnet IP addresses, and the leaves holds the IP addresses that are manually bound to
specific clients. The address pools that are of the same level are sorted by their
configuration precedence order. Such a structure enables configurations to be inherited.
That is, the configurations of the natural network segment can be inherited by its
subnets, whose configurations in turn can be inherited by their client address. So, for
the parameters that are common to the whole network segment or some subnets (such
as domain name), you just need to configure them on the network segment or the
corresponding subnets. The following is the details of configuration inheritance.
1) A newly created child address pool inherits the configurations of its parent address
pool.
2) For an existing parent-child address pool pair, when you performs a new
configuration on the parent address pool:
The child address pool inherits the new configuration if there is no corresponding
configuration on the child address pool.
The child address pool does not inherit the new configuration if there is already a
corresponding configuration on the child address pool.
Chapter 2 DHCP Server Configuration
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